1. Field of the Invention
The present invention relates to a switchgear and, more particularly, to a spring housing unit connected with a spring actuator in order to charge or discharge elastic force, as a means for accommodating a spring that provides a switching driving force of a switchgear.
2. Description of the Related Art
In general, in an electric power system or an electric power circuit for power transmission or transformation of electric energy, a switchgear is a device for opening or closing the electric power circuit between an electric power source and an electric load, earthing(grounding) the electric power circuit, or breaking the electric power circuit when a fault current such as a short-circuit current, or the like, occurs in the electric power circuit.
Since high voltage of thousands of volts or tens of thousands of volts is used in the electric power circuit, the switchgear must be configured to be received in a tank type metal container charged with inert insulating gas such as SF6 having excellent electrical insulating characteristics or configured to form an enclosure of constituent components of a switching mechanism for each pole (or phase) with a solid insulating material such as epoxy.
Such a switchgear comprises a stationary contactor electrically connected with an electric power source of the electric power circuit and having a contact, a movable contactor electrically connected with an electric load of the electric power circuit, being movable to a closing position at which the movable contactor can be in contact with the stationary contactor or an opening position at which the movable contactor is separated from the stationary contactor, a switching mechanism for driving the movable contactor to the closing position or the opening position, and a spring actuator for actuating a spring, which provides elastic energy as a driving source of the switching mechanism, to charge or discharge the elastic energy.
The switching mechanism may further comprise a closing spring providing elastic energy for driving the movable contactor to the closing position, a link mechanism transferring a driving force, an opening spring (in other words trip spring) for driving the movable contactor to the opening position, and a cam connected between the driving source and the closing spring and being rotatable to charge elastic energy in the closing spring.
The actuator may further comprise a driving motor for rotating the cam, a deceleration gear assembly, a charging gear, or the like.
FIG. 1 is a schematic view explaining a spring actuator according to the related art. With reference to FIG. 1, a spring actuator 1 may comprise a motor M, a driving gear 2 provided to a rotational shaft of the motor M, a deceleration gear meshed to the driving gear 2, and a charging gear 4 meshed to the deceleration gear 3. Although not shown, the spring actuator may further comprise a latch mechanism for restraining the charging gear 4 at a predetermined position and a releasing mechanism for releasing the latch mechanism.
The spring housing unit of the related art connected to the spring actuator comprises a spring 5 compressed or elongated according to a rotation of the charging gear to provide elastic energy for an opening position operation or closing position operation of the switchgear, and configured as a compression coil spring, a spring housing 6 accommodating the spring 5 therein and supporting one end of the spring 5 by a flange portion thereof, a cover 7 slidably installed in the spring housing 6 and supporting the other end of the spring 5, a connection rod 8 meshed to the cover 7 and having an outer circumferential surface formed as a threaded face, and a chain 9 having one end coupled to the connection rod 8 and the other end eccentrically coupled to the charging gear 4.
The spring 5 connected to the spring actuator according to the related art provides an energy source for the switchgear to actuate to the opening position and the closing position, which, thus, plays key role in the switchgear.
Meanwhile, a process of installing the spring 5 and assembling the spring housing 6 will be described.
With reference to FIG. 1, the spring 5 is positioned within the spring housing such that one end of the spring 5 is supported by the spring housing 6. Here, the spring 5 is not compressed. Next, the cover 7 enters the spring housing 6 through the other opened end of the spring housing 6, and then, meshed on an outer circumferential face of the connection rod 8.
Next, as can be understood from FIG. 2, the cover 7 is pressed by a spring jig 10 so as to be pushed into the spring housing 6, whereby the spring 5 is compressed by a predetermined initial compression length L between the movable cover 7 and an end portion (flange portion) of the fixed spring housing 6. After the spring 5 is compressed by the initial compression length L, the spring jig 10 is removed. Accordingly, the installation of the spring 5 in the spring housing 6 is completed.
In this state, the chain 9 connected to the connection rod 8 is connected to the charging gear 4 comprised in the spring actuator 1, whereby the connection of the assembly of the spring 5 and the spring housing 6 to the spring actuator 1 can be completed.
Namely, thereafter, the chain 9 is pulled by the driving of the spring actuator 1 to compress the spring 5 by the connection rod 8 and the cover 7 to charge electrical energy, and when a user requests closing the switchgear by manipulating a corresponding button, or the like, the corresponding elastic energy is discharged to drive the switching mechanism of the switchgear to the closing position.
However, in the related art spring housing unit, after completing assembling of the spring housing unit, a space corresponding to the initial compression length L unnecessarily remains at one side of the spring housing 6, causing a problem in which the size of the switchgear is increased by the corresponding initial compression length L.
Also, in the related art spring housing unit, in order to separate the spring housing 6 from the spring actuator 1, the initial charged energy of the spring 5 installed upon being compressed by the initial compression length L should be discharged by elongating the spring 5 by using the spring jig, and then, the spring housing 6 is separated from the spring actuator 1 in terms of safety of an operator, causing a problem in which the number of processes is increased and a great amount of time is required.